The principle of a traditional gas discharge lamp is shown in FIG. 1. Referring to FIG. 1, the circuit of a traditional gas discharge lamp comprises mainly a power factor correction circuit 10, a DC/DC converter 12, and an inverter 14. Those three can be connected in sequence, and the output of the inverter 14 can be connected with the gas discharge lamp 16.
As shown in FIG. 1, suitable power energy can be provided by the DC/DC converter 12 to the gas discharge lamp, and square wave voltage signal of low frequency (for example, 150 Hz) can be provided by the inverter 14 to the gas discharge lamp, these are the prior art and will not be further described herein.
The crest factor (a ratio of the peak current to the RMS current of the gas discharge lamp) is one of the parameters of the gas discharge lamp, and the crest factor is a significant parameter, which affects the life of the gas discharge lamp. Under an ideal condition, the value of the crest factor is one. However, since the peak current is usually larger than the RMS current in the practical application, the value of the crest factor may be larger than one in the practical application.
The larger the value of the crest factor is, the larger the peak current is, and this will cause the electrodes of the gas discharge lamp to be destroyed thereby cause the life of the gas discharge lamp to be decreased. Thus, in the gas discharge lamp circuit, an auxiliary circuit will be designed to reduce the peak current and to control the crest factor and to allow its value to be near an ideal value.